The aim was to generate new binders capable of specific binding to different target proteins with almost good affinity, while retaining the favorable folding and stability properties, and ease of bacterial expression of the parent molecule.
[6] Specific Affibody molecules binding a desired target protein can be “fished out” from pools (libraries) containing billions of different variants, using phage display.
Affibody molecules are based on a three-helix bundle domain, which can be expressed in soluble and proteolytically stable forms in various host cells on its own or via fusion with other protein partners.
Since they do not contain cysteines or disulfide bridges, they fold spontaneously and reversibly into the correct three-dimensional structures when the protection groups are removed after synthesis.
[20] Combination of small size, ease of engineering, high affinity and specificity makes Affibody molecules suitable alternative as monoclonal antibodies for both molecular imaging and therapeutical applications, especially for the receptor-overexpressing tumors.
[26][27][28][29] Anti-HER2 Affibody molecule, fused with albumin binding domain (ABD), denoted as ABY-027, labeled with Lutetium-177 provided reduction of renal and hepatic uptake of radioactivity in mice xenografts.